fix(utf8): Fix multiple metric name inside braces validation (#691)

* Fix multiple metric name inside braces validation

Signed-off-by: Federico Torres <federico.torres@grafana.com>

---------

Signed-off-by: Federico Torres <federico.torres@grafana.com>

Author: fedetorres93

expfmt/text_parse.go

@@ -75,7 +75,9 @@ type TextParser struct {
 	// count and sum of that summary/histogram.
 	currentIsSummaryCount, currentIsSummarySum     bool
 	currentIsHistogramCount, currentIsHistogramSum bool
-	currentMetricIsInsideBraces                    bool
+	// These indicate if the metric name from the current line being parsed is inside
+	// braces and if that metric name was found respectively.
+	currentMetricIsInsideBraces, currentMetricInsideBracesIsPresent bool
 }
 
 // TextToMetricFamilies reads 'in' as the simple and flat text-based exchange
@@ -147,6 +149,7 @@ func (p *TextParser) reset(in io.Reader) {
 func (p *TextParser) startOfLine() stateFn {
 	p.lineCount++
 	p.currentMetricIsInsideBraces = false
+	p.currentMetricInsideBracesIsPresent = false
 	if p.skipBlankTab(); p.err != nil {
 		// This is the only place that we expect to see io.EOF,
 		// which is not an error but the signal that we are done.
@@ -301,17 +304,24 @@ func (p *TextParser) startLabelName() stateFn {
 	}
 	if p.currentByte != '=' {
 		if p.currentMetricIsInsideBraces {
-			if p.currentMF != nil && p.currentMF.GetName() != p.currentToken.String() {
-				p.parseError(fmt.Sprintf("multiple metric names %s %s", p.currentMF.GetName(), p.currentToken.String()))
+			if p.currentMetricInsideBracesIsPresent {
+				p.parseError(fmt.Sprintf("multiple metric names for metric %q", p.currentMF.GetName()))
 				return nil
 			}
 			switch p.currentByte {
 			case ',':
 				p.setOrCreateCurrentMF()
+				if p.currentMF.Type == nil {
+					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
+				}
 				p.currentMetric = &dto.Metric{}
+				p.currentMetricInsideBracesIsPresent = true
 				return p.startLabelName
 			case '}':
 				p.setOrCreateCurrentMF()
+				if p.currentMF.Type == nil {
+					p.currentMF.Type = dto.MetricType_UNTYPED.Enum()
+				}
 				p.currentMetric = &dto.Metric{}
 				p.currentMetric.Label = append(p.currentMetric.Label, p.currentLabelPairs...)
 				p.currentLabelPairs = nil

expfmt/text_parse_test.go

@@ -594,6 +594,49 @@ request_duration_microseconds_count 2693
 				},
 			},
 		},
+		// 11: Multiple minimal metrics with quoted metric names.
+		{
+			in: `
+{"name.1"} 1
+{"name.2"} 1
+{"name.3"} 1
+`,
+			out: []*dto.MetricFamily{
+				{
+					Name: proto.String("name.1"),
+					Type: dto.MetricType_UNTYPED.Enum(),
+					Metric: []*dto.Metric{
+						{
+							Untyped: &dto.Untyped{
+								Value: proto.Float64(1),
+							},
+						},
+					},
+				},
+				{
+					Name: proto.String("name.2"),
+					Type: dto.MetricType_UNTYPED.Enum(),
+					Metric: []*dto.Metric{
+						{
+							Untyped: &dto.Untyped{
+								Value: proto.Float64(1),
+							},
+						},
+					},
+				},
+				{
+					Name: proto.String("name.3"),
+					Type: dto.MetricType_UNTYPED.Enum(),
+					Metric: []*dto.Metric{
+						{
+							Untyped: &dto.Untyped{
+								Value: proto.Float64(1),
+							},
+						},
+					},
+				},
+			},
+		},
 	}
 
 	for i, scenario := range scenarios {